This invention relates to the field of optical communication systems and more particularly to a system for beam-steering using a reference signal feedback.
Optical communication systems include optical components, such as optical fibers coupled to switching components, that receive, transmit, and otherwise process information in optical signals. The switching components in an optical communication system selectively direct the information carried by the optical signal to one or more other optical components. Existing optical communication systems are limited in a number of ways. One problem is that the scaleability of prior optical systems is limited by the difficulty associated with manufacturing the optical components of the system according to precise specifications having small tolerances for error. Another problem is that various adverse conditions existing during the switching operation may cause a deviation of the switching components resulting in a misalignment between the optical signal and the optical components. This results in a loss of a portion of the optical signal.
A system for beam-steering using a reference signal feedback is provided that substantially eliminates or reduces disadvantages and problems associated with previous optical systems.
In accordance with one embodiment of the present invention, a system for processing an optical signal includes a reflector that reflects an input optical signal to a selected one of a plurality of output waveguides and that reflects a reference optical signal associated with the input optical signal. A detector detects a position coordinate of the reference optical signal. A feedback module coupled to the detector generates a control signal based upon the detected position coordinate. An actuator coupled to the reflector positions the reflector in response to the control signal.
Another embodiment of the present invention is a method for processing an optical signal that includes reflecting an input optical signal to a selected one of a plurality of output waveguides using a reflector. The method continues by reflecting a reference optical signal using the reflector, wherein the reference optical signal is associated with the input optical signal. The method continues by detecting a position coordinate of the reference optical signal and by generating a control signal based upon the detected position coordinate. The method concludes by positioning the reflector in response to the control signal.
Technical advantages of the present invention include a system for processing an optical signal that performs a calibration operation and a switching operation. During the calibration operation, an input waveguide emits an input optical signal that is directed to a selected output waveguide by a reflector. An input device emits a reference signal that is directed to a position detector by the reflector. The reference signal maintains a predetermined angular correspondence to the input optical signal. An optical power meter measures the light intensity of the input optical signal received by the selected output waveguide. When the reflector is placed in an alignment position such that the input optical signal is substantially aligned with the output waveguide, the light intensity of the input optical signal measured by the optical power meter reaches a predetermined threshold. At this point, the position coordinate of the reference signal detected by the position detector is stored as an expected position coordinate by a memory of a feedback module.
During the switching operation, the input waveguide emits the input optical signal that is directed to the selected output waveguide by the reflector. The input device emits the reference signal that is directed to the position detector by the reflector. The reference signal maintains an angular correspondence with the input optical signal such that any deviation between the position coordinate of the reference signal detected by the position detector and the expected position coordinate of the reference signal measured during the calibration operation indicates a misalignment between the input optical signal and the output waveguide. A feedback controller generates a control signal based upon the difference between the expected position coordinate and the detected position coordinate of the reference signal. In this respect, the present invention determines a xe2x80x9ccorrection factorxe2x80x9d that is then used by an actuator to position the reflector in the appropriate alignment position.
The present invention uses active positional feedback of the reference signal in conjunction with calibrated alignment characteristics to switch the input optical signal from the input waveguide to the output waveguide and to correct any misalignments between the input optical signal and the output waveguide. In this respect, the present invention provides many technical advantages. For example, the present invention relaxes the design tolerances associated with precisely aligning the optical components of the system during manufacture. As a result, the present invention facilitates a scaleable optical switch. Furthermore, the present invention provides superior optical performance during the switching operation. For example, the reference signal supports determining any misalignments between the input signal and a selected output waveguide without extracting or diverting any portion of the input signal during the switching operation. Moreover, by using a reference signal feedback to place the reflector in the appropriate alignment position, the present invention facilitates switching an input optical signal from an input optical fiber to an output optical fiber with superior optical coupling and accuracy. The present invention therefore provides fiber-to-fiber optical switching that results in switching speeds of approximately one millisecond.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.